16.1 Voice, Data Link, Position Reports, and Lost Communications

Communication Is a Completed Exchange

Aircraft dispatch communications connect the flight to operational-control support, while ATC communications provide traffic clearances and coordination. The two functions overlap in an emergency but are not interchangeable in ordinary operations. A dispatcher must understand each system's range, intended recipient, approval, latency, and fallback. A transmitted message that has not been received or understood is an incomplete safety communication.

Voice and coverage

VHF generally provides line-of-sight communications and is widely used in terminal and continental operations. Terrain, altitude, range, antenna/system status, and assigned frequencies affect availability. HF supports longer-range communications through propagation that can vary with atmosphere and ionospheric conditions. Satellite voice offers another path where approved and available, but coverage and reliability still need to be evaluated for the route and possible diversion altitudes.

SELCAL (selective calling) alerts a crew to an addressed call on a monitored communications arrangement. It does not itself carry a complete ATC clearance, supply aircraft position, or eliminate the need to establish the associated communication. Verify the appropriate checks and calling arrangements under the approved regional/company procedure rather than assuming a successful alert test proves all links remain available throughout flight.

Data links and surveillance

The medium and application differ. ACARS may use VHF, HF, or satellite transmission. CPDLC and ADS-C require the appropriate aircraft, system, operator, and airspace arrangements. A company ACARS reply does not prove an ATC CPDLC logon, and an ADS-C report does not represent PIC concurrence with a dispatch amendment.

Ordinary regulatory requirements

Section 121.99 requires domestic/flag route communications providing reliable and rapid links between the aircraft and dispatch and ATC through direct or approved arrangements. Except in an emergency, company dispatch systems must be independent of systems operated by the United States. Flag ETOPS adds the applicable voice and additional-system requirements, considering possible diversion routes and altitudes.

Supplemental flight following uses the approved §§ 121.125/127 arrangements and does not universally have the same inflight-center monitoring requirement. Before accepting a communication deferral, check the actual operation and authorization. A usable link on the planned cruise route does not automatically satisfy a lower diversion route or the required additional ETOPS path.

Protocol and workload

Identify the flight and intended recipient. State the operational issue, relevant time/location, required action or decision, and acknowledgment needed. Use clear units and UTC dates where applicable. Avoid ambiguous statements such as “alternate bad” when the crew needs to know which airport, what condition, when it applies, and what verified alternatives exist.

For a release amendment, distinguish an information update from a requested operational decision. Obtain the required PIC concurrence and record the completed exchange under the approved procedure. A data-link transmission status can show technical delivery while the crew has not yet reviewed the operational content. During takeoff, approach, or an emergency, prioritize concise safety information and use the carrier's appropriate urgent-contact method.

Position reports

Conventional voice position reporting can include aircraft identity, position and time, level, next position/estimate, and subsequent position as required by the applicable procedure. Automated reporting has its own contract and equipment conditions. Use the actual regional and company requirements; do not mandate every field on every radar-monitored domestic flight.

Dispatch compares progress with the planned route, estimated times, fuel trends, and relevant weather. An unexplained missing report triggers the approved follow-up and overdue process. A surveillance position and a company fuel report can originate at different times; do not combine them as if simultaneous without checking timestamps.

Lost communications under U.S. IFR rules

Section 91.185 first addresses operation in VFR conditions: if VFR is encountered, continue under VFR and land as soon as practicable. If IFR must continue, the route priorities are assigned, the route to the specified fix/route/airway when being radar vectored, the expected route where applicable, and the filed route when neither assigned nor expected applies. Use the highest of the last assigned altitude, applicable minimum IFR altitude, or altitude ATC advised may be expected, as applicable to the segment.

Clearance-limit timing is a separate test in § 91.185(c)(3). If the limit is a fix from which an approach begins, commence descent/approach as close as possible to the EFC time received, or the appropriate filed/amended ETA if none was received. If it is not such a fix, leave at EFC if received, or on arrival if none, then proceed to an approach-start fix and commence as close as possible to the applicable ETA. An EFC does not create one universal timing instruction for every enroute hold.

Dispatcher support during failure

Attempt approved alternate links and coordinate relevant information with ATC and company contacts. Avoid inventing an aircraft clearance. The PIC follows the applicable rules and aircraft procedures; oceanic and foreign contingencies may have additional regional requirements. If a known inflight emergency requires dispatcher action and contact with the pilot cannot be established, § 121.557(b) requires declaring an emergency and taking necessary action.

For a fictional data-link failure, voice contact remains available and the flight is in radar coverage. Confirm which authorization or reporting function has failed, use the approved fallback, and evaluate route/capability effects. Do not treat every failed ACARS printer as total ATC radio failure, and do not treat a working company phone patch as proof that the original navigation/surveillance authorization remains satisfied.

Official References

Source check: 2026-10-12. FAA AIM clearances and flight plans; Lost communications § 91.185; Route communications § 121.99; FAA dispatcher PTS. For operational use, apply current issued authorizations and the assigned aircraft’s approved data.